I think I will go against the voting result ....(why doing a survey you ask ??? I gave me the time to think).

I will try a separated paid app.First it is more secure, your app purchase is registered in the Google Store, you can't lose it by uninstalling your app, like the keys.Second, it is simpler for the user, and it gives a sens of a real product, not something patched with micro-transactions.Third, I will make this fully unlocked app mainly for those who hate micro-transaction, it will go against the main goal if a player must pass through micro-transaction.Fourth, it will split the reviews. All those who complains about the game not being free, will not populate the unlocked paid app.